On a bright November day in Jordan, the Dead Sea appears tranquil, with barely a ripple on its surface as it stretches out into a distant haze.

But there are indications that all is not well here at the lowest point on Earth: by the cluster of hotels that lines the seafront, mechanical diggers appear to be shoring up the land, and the walk down to the sun loungers beside the water is lengthening.

It all hints at a problem that has vexed multiple governments and sparked concerns among researchers, environmentalists and anyone else with an interest in this iconic salt lake, which is woven into the history of Islam, Christianity and Judaism.

In short, the Dead Sea is dying.

It faces a threat that embodies many of the modern-day challenges in the Middle East over hard-pressed water resources.

Turn the clock back about half a century, and the Dead Sea's surface area was almost 1,000 square kilometres, a figure that had remained roughly constant in records going back to the beginning of the 18th century.

Since the 1960s, though, it has shrunk at what few would deny is an alarming rate. It now covers about 667 square kilometres and its water level is dropping by a remarkable 1.4 metres per year.

The Dead Sea's retreat has exposed new areas of land and caused freshwater to move into underground salt deposits, dissolving them and creating enormous voids into which the terrain above simply collapses. In just a few decades, as many as 6,000 sinkholes have appeared, about 1,000 of them are in Jordan. Some are vertiginous openings tens of metres deep.

No one understands these effects better than Professor Najib Karaki, a geophysicist from the University of Jordan who has been researching events here since 1991.

"Nothing will reverse the damage," he says, while adding that concerted efforts can, however, limit the consequences of the Dead Sea's continued shrinkage.

Prof Karaki has countless photographs showing the consequences of building on land that subsequently becomes unstable: buildings perched precipitously on the edge of widening openings, bridges that have collapsed, roads that have been diverted.

The reason why the Dead Sea is shrinking is simple, even if the politics behind it are complex and a source of controversy that dates back many decades: much less water is flowing in from the River Jordan. In the 1960s, says Karaki, about 1.3 billion cubic metres spilled into the Dead Sea each year. Now the figure is "not more than 200 million, 300 million" cubic metres.

Much of the decline is because of heavy extraction by Jordan and Israel, with the latter using the water to irrigate the Negev desert, which lies in the south and covers more than half the total area of the country. Jordan is one of the most water-stressed countries in the world, and renewable sources can only provide about half of what the population needs, according to USAID.

While the Dead Sea problem is on a grand scale, so is the proposed remedy, the Red Sea-Dead Sea Water Conveyance Project, often abbreviated to the Red-Dead project. This aims to provide drinking water and to produce electricity as well as dealing with the fall in the Dead Sea's water level.

Jordan hopes that this scheme will, to start with, pump 300 million cubic metres of water from the Red Sea to the Dead Sea. Local press reports quoting the Jordanian authorities suggest that if the project is fully realised, 2 billion cubic metres could be transferred each year.

A memorandum of understanding over the project was signed between Jordan, Palestine and Israel four years ago.

The Jordanian authorities have said that $400 million out of an initial cost of $1.1 billion has already been pledged by donors, with major contributions, as grants, loans and equipment, coming from the United States, Japan, the European Union, Italy, Spain and others. Construction could start next year, although recent reports have highlighted tensions between Israel and Jordan over the scheme.

Prof Karaki does not think it likely that the project will ever be able to provide enough water to stem the continued decline in the level of the Red Sea. He says the initial stage would only provide "a very tiny percentage" of what is needed and even long-term he sees it as something that will only "limit" the problems rather than solve them.

His approach, instead, is one of mitigation, of trying to ensure that building projects around the Dead Sea do not fall victim to the area's now notorious physical instability.

He hopes to complete a complex survey of the land surrounding the Dead Sea using new satellite data and going back through recent historical records to group blocks of land into three categories: completely safe for development, safe as long as significant engineering work is carried out to ensure stability, and best left undeveloped because of the risk of damage. It would offer, he says, an "early-warning system".

"If you want to make an investment in an area, we can show you how it performed in the last 20 years," he says.

As for the future of the Dead Sea itself, which has a maximum depth of about 300 metres, Prof Karaki says its level will, eventually, settle, albeit significantly below where it is now.

"It's not going to disappear completely ... There will always be some water coming [into it] and it will stabilise," he said.

"When it reaches a new equilibrium it will be very much less than nowadays."